Field of the Invention
The invention relates to a controller with an actuator having a controllable length that is accommodated in a housing. The invention also relates to a device for transmitting a deflection of an actuator, in particular of a piezoelectric actuator.
A controller with a piezoelectric actuator is used in automotive engineering, for instance for opening an injection valve of an internal combustion engine. A longitudinal motion of the piezoelectric actuator is transmitted through a suitable configuration to an associated valve closing member, which relieves a back side of a pressure-loadable nozzle needle and thus enables a targeted opening and closure of the injection nozzle.
A piezoelectric actuator, which is known from UK Patent Application GB 2 193 386 A, rests on a diaphragm that defines a pressure chamber which is filled with hydraulic fluid, along with portions of a valve housing and a tappet disposed movably in a guide bore. The diaphragm protects the piezoelectric actuator from being wetted with the hydraulic fluid. The diaphragm is disposed substantially perpendicular to the direction of deflection of the piezoelectric actuator and is secured laterally in the valve housing.
Another version also protects the tappet against being wetted with the hydraulic fluid. There the pressure chamber is defined by a first bellows, which has a platform-like part on which the piezoelectric actuator rests and which extends substantially perpendicular to the direction of motion of the piezoelectric actuator and is tightly joined to the valve housing. The tappet, which is disposed movably in a guide bore, is also joined to the valve housing by a second bellows, which is disposed perpendicular to the direction of motion of the tappet inside the guide bore. The first bellows and the second bellows form a pressure chamber filled with hydraulic fluid. The piezoelectric actuator, as well as the tappet, are both being protected against being wetted with the hydraulic fluid.